Mobile wireless communication devices, such as a cellular telephone or a wireless personal digital assistant, can provide a wide variety of communication services including, for example, voice communication, text messaging, internet browsing, and electronic mail. Mobile wireless communication devices can operate in a wireless communication network of overlapping “cells”, each cell providing a geographic area of wireless signal coverage that extends from a radio network subsystem located in the cell. The radio network subsystem can include a base transceiver station (BTS) in a Global System for Communications (GSM) network or a Node B in a Universal Mobile Telecommunications System (UMTS) network. Newer mobile wireless communication devices can include the capability of providing several different communication services simultaneously, such as a voice call and data internet browsing at the same time. A separate radio access bearer can be used to transport radio link signals for each of the services between the mobile wireless communication device and one or more radio network subsystems in the wireless network. One radio access bearer can be used for the voice call, and a separate radio access bearer can be used for the data internet browsing. An additional radio access bearer can also be used for signaling messages communicated between the mobile wireless communication device and the wireless network.
From the perspective of a user of the mobile wireless communication device, each of the communication services transported over the separate radio access bearers can be considered independent, and therefore changes to a connection through one radio access bearer should impact minimally connections using a separate radio access bearer. Certain communication protocols, such as the 3'd Generation Partnership Project (3GPP) UMTS specifications, can treat a multiple radio access bearer connection as a single connection, resulting in multiple services changed together rather than separately. A reset of a multiple radio access bearer connection due to errors on a data carrying radio access bearer or on a signaling radio bearer can cause a simultaneous voice connection that uses a separate voice carrying radio access bearer to terminate. Loss of the voice connection can be immediately apparent to the user, while loss of the data connection can be perceived as a delay in transmission until the data connection is restored. For mobile wireless communication devices that support simultaneous voice and data connections, it can be preferable to maintain a voice connection even when the simultaneous data connection (or a concurrent signaling connection) can operate with limited performance.
Data usage through wireless communication networks has increased substantially with the introduction of advanced mobile wireless communication devices. As the number of data users has increased, the wireless communication networks can incur congestion and scheduling issues that affect the delivery of data to the mobile wireless communication device. In some situations, a mobile wireless communication device connected simultaneously by a voice connection and a data connection can continue to receive voice signals that can provide intelligible voice over the voice connection when no data or acknowledgements are received from the network over the data connection. The mobile wireless communication device can be configured to retransmit, reset and ultimately terminate the radio link with the wireless communication network when the data connection appears unrecoverable. Terminating the radio link, however, can remove both the data connection and the voice connection, even though the voice connection can be operating properly.
Even when a data connection can provide reliable transmission of data packets, the wireless network can reconfigure the data connection during an active connection to change properties of one or more radio access bearers between the mobile wireless communication device and the wireless access network. Reconfiguration of a radio access bearer can be used to change a transmission data rate to match current usage by the mobile wireless communication device with the wireless access network, effectively providing a dynamic allocation of radio resources based on past, current or predicted usage. Similarly a radio access bearer can be reconfigured between different radio access technologies, or different versions thereof, that can offer different transmission properties and use different processing requirements. Some configurations can consume more power at the mobile wireless communications device than others, and a tradeoff between data transmissions rates for throughput and power consumption for battery usage can be realized by dynamically adapting configuration of the radio access bearers.
Reconfiguration of radio access bearers can be accomplished through a series of messages exchanged between the mobile wireless communication device and a wireless access network. For a connection between the mobile wireless communication device and the wireless access network operating with low quality, such as low received signal code power, an exchange of reconfiguration messages can occupy limited radio resources and be prone to incurring errors, potentially resulting in dropped connections if the reconfiguration messages cannot be received properly within established time limits. Reconfiguration messages can be both long and numerous, and therefore have a higher probability of incurring errors during transmission than relatively shorter signaling messages. While error checking and retransmission mechanisms can partially compensate for transmission errors to ensure correct reception of signaling messages, strict time-out requirements can result in resets when timely reception of a sequence of signaling messages cannot be completed.
Thus there exists a need to control the reconfiguration of one or more radio access bearers in a multiple radio access bearer connection between a mobile wireless communication device and radio network subsystem in a wireless communication network.